Mechanical alloying of MgNi compounds under hydrogen and inert atmosphere

The effect of milling atmosphere on the nature and composition of milled products was investigated. Pure magnesium and the mixture 2Mg + Ni were milled in a planetary ball mill under hydrogen atmosphere. The mixture 2Mg + Ni was also milled under argon atmosphere. X-ray powder diffraction, SEM and DSC measurements were taken at certain intervals during the milling process. When milled under hydrogen, pure magnesium formed MgH₂. DSC measurement indicated that the onset temperature of MgH₂ decomposition was 440.7°C. Magnesium hydride was also formed when the mixture 2Mg + Ni was milled under hydrogen. The presence of nickel lowered the onset temperature of MgH₂ decomposition to 225.4°C. By milling the mixture 2Mg + Ni under argon, Mg₂Ni was produced. The presence of Mg₂Ni slowed the decomposition kinetics of MgH₂.